I've had my Quadra Fire Santa Fe stove for 10 years now and it's been great. The last few days, however, it seems like the fire pot has been filling about half way with glowing coals while running with more pellets coming down all the time and taking a long time to burn down when set temp is reached. It appears to be safe enuf, but I'm concerned about the amount of fuel it's burning.....and it doesn't seem right. I'm burning a premium grade of Fir pellets. Hasn't been like this before. Any thoughts ?? Thanks.